kishk is one of the important fermented dairy products in iran that is suitable for contamination of pathogenic and spoilage microorganisms. the effect of power ultrasound waves (130 w, 20 khz) was investigated on staphylocuccos areus and escherichia coli in liqud kashk. the results of variance analysis indicated that population of these microorganisms significantly (p0/05).

In forest clearings of the Malaysian rainforest, chirping and trilling Mecopoda species often live in sympatry. We investigated whether a phenomenon known as stochastic resonance (SR) improved the ability of individuals to detect a low-frequent signal component typical of chirps when members of the heterospecific trilling species were simultaneously active. This phenomenon may explain the fact ...

Audiogram: A graph of hearing ability charting frequency (abcissa) vs. sensitivity measured as sound pressure or intensity (ordinate). Cetaceans: Whales and dolphins decibel (dB): a scale based on the log ratio of two quantities. It is commonly used to represent sound pressure level or sound intensity. The value of the decibel depends upon the denominator used, or reference pressure. Therefore ...

There are different mechanisms of seabed scattering which are due to different types of seabed medium irregularities, which are roughness of the seabed interfaces, and volume heterogeneity: continuous (spatial fluctuations of the sediment acoustic parameters) and discrete scatterers (or sediment inclusions, such as relatively large shells and shell fragments). Given different environmental cond...

An optimal control algorithm for generating purely phase-modulated pulses is derived. The methodology is applied to obtain broadband excitation with unprecedented tolerance to RF inhomogeneity. Design criteria were transformation of Iz-->Ix over resonance offsets of +/-25 kHz for constant RF amplitude anywhere in the range 10-20 kHz, with a pulse length of 1 ms. Simulations transform Iz to grea...

Due to their high stiffness, small dimensions and low mass, piezoelectric stack actuators are capable of developing large displacements with bandwidths of greater than 100 kHz. However, due to their large electrical capacitance, the associated driving amplifier is usually limited in bandwidth to a few kHz. In this paper the limiting characteristics of piezoelectric drives are identified as the ...

A variable-duration notched-noise experiment was conducted in a noise context. Broadband noise preceded and followed a tone and notched noise of similar duration. Thresholds were measured at four durations (10, 30, 100, and 300 ms), two center frequencies (0.6, 2.0 kHz), and five relative notch widths (0.0, 0.1, 0.2, 0.4, 0.8). At 0.6 kHz, 10-ms thresholds decrease 6 dB across notch widths, whi...

The specific acoustic impedance of the cochlear partition was measured from 4 to 20 kHz in the basal turn of the gerbil cochlea, where the best frequency is approximately 40 kHz. The acoustic impedance was found as the ratio of driving pressure to velocity response. It is the physical attribute that governs cochlear mechanics and has never before been directly measured, to our knowledge. The ba...